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Wed, 07 Aug 2024 10:00:22 -0700 (PDT) Received: from thinkpad ([120.60.60.211]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1ff592ad9e4sm108304425ad.283.2024.08.07.10.00.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Aug 2024 10:00:21 -0700 (PDT) Date: Wed, 7 Aug 2024 22:30:11 +0530 From: Manivannan Sadhasivam To: Bjorn Helgaas Cc: Anand Moon , Lorenzo Pieralisi , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Rob Herring , Bjorn Helgaas , Heiko Stuebner , linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH linu-next v1] PCI: dw-rockchip: Enable async probe by default Message-ID: <20240807170011.GC5664@thinkpad> References: <20240625155759.132878-1-linux.amoon@gmail.com> <20240807163106.GA101420@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20240807163106.GA101420@bhelgaas> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240807_100024_178283_31F4FE9E X-CRM114-Status: GOOD ( 29.08 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Aug 07, 2024 at 11:31:06AM -0500, Bjorn Helgaas wrote: > On Tue, Jun 25, 2024 at 09:27:57PM +0530, Anand Moon wrote: > > Rockchip PCIe driver lets waits for the combo PHY link like PCIe 3.0, > > PCIe 2.0 and SATA 3.0 controller to be up during the probe this > > consumes several milliseconds during boot. > > This needs some wordsmithing. "driver lets waits" ... I guess "lets" > is not supposed to be there? I'm not sure what the relevance of "PCIe > 3.0, PCIe 2.0, SATA 3.0" is. I assume the host controller driver > doesn't know what downstream devices might be present, and the async > probing is desirable no matter what they might be? > Since the DWC driver is enabling link training during boot, it also waits for the link to be 'up'. But if the device is 'up', then the wait time would be usually negligible (few ms). But if there is no device, then the wait time of 1s would be evident. But here the patch is trying to avoid the few ms delay itself (which is fine). The type of endpoint might have some impact on the link training also. But async probe is always preferred. - Mani > > Establishing a PCIe link can take a while; allow asynchronous probing so > > that link establishment can happen in the background while other devices > > are being probed. > > > > Signed-off-by: Anand Moon > > --- > > drivers/pci/controller/dwc/pcie-dw-rockchip.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c b/drivers/pci/controller/dwc/pcie-dw-rockchip.c > > index 61b1acba7182..74a3e9d172a0 100644 > > --- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c > > +++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c > > @@ -367,6 +367,7 @@ static struct platform_driver rockchip_pcie_driver = { > > .name = "rockchip-dw-pcie", > > .of_match_table = rockchip_pcie_of_match, > > .suppress_bind_attrs = true, > > + .probe_type = PROBE_PREFER_ASYNCHRONOUS, > > }, > > .probe = rockchip_pcie_probe, > > }; > > -- > > 2.44.0 > > > -- மணிவண்ணன் சதாசிவம்